Workpiece presentment to a processing device

ABSTRACT

A workpiece presentment system and associated method for workpiece presentment with a pick and place device is provided. The system includes a pair of parallel stationary rails, and first and second shuttle rails respectively disposed adjacent first and second ends of the stationary rails. Each shuttle rail is independently moveable laterally to a longitudinal alignment with a selected one of the pair of stationary rails. A control circuit is configured to circulate only two pallets simultaneously in the same rectangular path of travel to load trays to the pallets on one of the stationary rails while presenting the trays to the pick and place device on the other stationary rail.

BACKGROUND

Manufacturing operations have significantly evolved in complexitythrough the integration of sophisticated automation devices andassociated methods. Gains have been realized both in productivity andreliability as past reliance on human judgment and manipulation has beenreplaced by processor-based systems.

An example of this is manifested in the sophistication of productionequipment used at final assembly. Manufacturers are continually strivingto replace manual assembly operations with highly complex processorcontrolled automated systems. They are reengineering existing factoriesto pull components through the manufacturing process and assemble themjust in time at final assembly, instead of batch processing ofsubassemblies as was more prevalent in the past.

But any gains in speed and repeatability from automating are forfeitedif flexibility is forsaken. For example, given no constraints in the wayof budget, space, time, and assembly line changeovers, the skilledartisan can likely construct a dedicated purpose robot for a givenprocess. Pick and place robots, for example, usually consist ofadversely large, complex, and expensive three axis manipulators movingbetween a queue of workpieces and an assembly line. What is lacking is acompact and highly flexible system that is adaptable for changing theworkpieces it processes on the fly, that maximizes process utilizationby minimizing the travel between the workpiece queue and the point ofassembly, and that operates at near 100% utilization with respect tocontinuously supplying the next workpiece in the queue for picking andplacing. It is to those needed improvements in the art that the claimedembodiments are directed.

SUMMARY

Embodiments of the present invention are generally directed to workpiecepresentment devices in an automated processing environment.

In some embodiments a workpiece presentment system and associated methodfor workpiece presentment with a pick and place device is provided. Thesystem includes a pair of parallel stationary rails, and first andsecond shuttle rails respectively disposed adjacent first and secondends of the stationary rails. Each shuttle rail is independentlymoveable laterally to a longitudinal alignment with a selected one ofthe pair of stationary rails. A control circuit is configured tocirculate two pallets simultaneously in the same rectangular path oftravel to load trays to the pallets on one of the stationary rails whilepresenting the trays to the pick and place device on the otherstationary rail.

These and various other features and advantages which characterize theclaimed embodiments will become apparent upon reading the followingdetailed description and upon reviewing the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric depiction of a workpiece presentment system thatis constructed in accordance with embodiments of the claimed invention.

FIG. 2 is an elevational depiction of the workpiece presentment systemof FIG. 1.

FIG. 3 diagrammatically depicts the rectangular path of travel taken byboth pallets in the workpiece presentment system of FIG. 1.

FIG. 4 isometrically depicts the tray feeder of the workpiecepresentment system of FIG. 1.

FIG. 5 is a functional block depiction of the control circuit of theworkpiece presentment system of FIG. 1.

FIG. 6 depicts an end view of the stationary rails and the shuttlerails.

FIG. 7 depicts an isometric view of the tray feeder with an automatedtray stacker and an automated tray destacker.

FIGS. 8-13 diagrammatically depict snapshots of the pallets as theytraverse the rectangular path of travel.

DETAILED DESCRIPTION

Referring to the drawings in general, and for now more particularly toFIG. 1 that shows a workpiece presentment system 100 that is constructedin accordance with the claimed embodiments. The workpiece presentmentsystem 100 generally has a pick and place device 102 and a tray feeder104. The tray feeder 104 presents a continuous supply of workpieces 106that are packaged in rows in a tray 108.

In the illustrative embodiments the pick and place device 102 hasfreedom of movement in two axes. A horizontal gantry 110 moves an endeffector 112 (FIG. 2) between workpieces 106 in the currently presentedtray 108 and an assembly line 114. The elevation of the end effector 112is controlled by a z-axis fluid powered cylinder 116.

FIG. 2 depicts a side elevational view of the workpiece presentmentsystem 100. Note that one of the support members 117 is depicted in tearaway fashion in order to more clearly view the things of interest. FIG.2 shows the trays 108 being carried by pallets 118, 120 that are, inturn, supported by stationary rails 122, 124, respectively. As willbecome clear below, the pallet 118 is also sometimes supported by thestationary rail 124, and the pallet 120 is also sometimes supported bythe stationary rail 122.

Motors 126, 128 drive respective powered rollers 130, 132. A pair oftangs 134, 136 depends from each of the respective pallets 118, 120. Oneof the tangs 134, 136 is frictionally engaged between the poweredrollers 130, 132 and a pinch roller 138, 140. It will be noted that thetang 134 of pallet 118 is engaged for moving it on the stationary rail122, while the other tang 136 of pallet 120 is engaged for moving it onthe stationary rail 124. The reason for two tangs 134, 136 will be clearbelow in the description of how the pallets 118, 120 are shuttled to thestationary rails 122, 124. Positional control of each pallet 118, 120 asit is moved longitudinally along the rails 122, 124 is provided by alinear encoder, which may be integral to the rails 122, 124 or aseparate component thereof.

FIG. 3 is a diagrammatic depiction of the rectangular path of travelthrough which both pallets 118, 120 traverse in order to continuouslypresent workpieces 106 to the pick and place device 102. In theseillustrative embodiments the pick and place device 102 processes theworkpieces 106, depicted as there being five workpieces 106 in each row,from the tray 108 to the assembly line 114. It will be understood thatin alternative equivalent embodiments the reverse may occur; that is,the pick and place device 102 can process workpieces 106 from theassembly line 114 to the trays 108.

The tray 108 depicted in solid lines is currently presenting rows of theworkpieces 106 to the pick and place device 102. Two workpieces 106 haveyet to be picked from the tray 108 in the currently presented row. Afterthe last of those two workpieces 106 is picked, the pallet 118, 120supporting the tray 108 will incrementally it, by an amountcorresponding to the distance between two adjacent rows, in order topresent the next row of workpieces 106 to the pick and place device 102.

In the corners of the rectangular path of travel different states and/oractivities are depicted by pallets 118, 120 drawn in broken lines. Forexample, when the tray 108 traverses to the lower right hand corner ithas been fully presented to the pick and place device 102. In otherwords, in this illustrative example the tray 108 has been emptied of allworkpieces 106. The pallet 118, 120 then shuttles laterally to the upperright-hand corner where the fully presented tray 108 is removed from thepallet 118, 120. The pallet 118, 120 then moves to the left-hand cornerwhere a new tray 108 is placed on the pallet 118, 120. The removal oftrays 108 from the pallet 118, 120 and the placing new trays 108 to thepallet 118, 120 is preferably performed by an automated process, asdescribed below. The new tray 108 is then shuttled laterally again intooperable alignment with the pick and place device 102.

The two pallets 118, 120 independently traverse this same rectangularpath of travel so that during the time that one of them is presentingworkpieces 106 to the pick and place device 102, the other one isunloading its fully presented tray 108 and receiving a new tray 108. Thesequencing is preferably timed so that before the current tray 108 isfully presented, the next unpresented tray 108 has been reoriented inthe end-to-end relationship. That way, the cycle time associated withprocessing workpieces in the last row of one tray 108 and the first rowof another tray 108 is substantially the same as the cycle timeassociated with processing any two adjacent rows in one tray 108.

FIG. 4 is an isometric depiction of the tray feeder 104 at a time whenthe pallet 118 is in position to present a tray 108 to the pick andplace device 102, while the pallet 120 is in position to receive a newtray. To shuttle the pallets 118, 120 between the two stationary rails122, 124, a shuttle rail 142 is supported by a base 144 which is, inturn, subject to lateral positioning as determined by a fluid cylinder146. Another shuttle rail 143 (FIG. 11) is likewise moved laterally by afluid cylinder 148 at the other end of the stationary rails 122, 124.The shuttle rail 143 is hidden from view in FIG. 4 by the pallet 120that is supported upon it. The shuttle rails 142, 143 are moveableindependently of each other by independent actuation of the respectivefluid powered cylinders 146, 148.

The shuttle rail 142 in FIG. 4 is still in alignment with the stationaryrail 124 from having previously shuttled the pallet 120 from thestationary rail 122. As pallet 122 continues to traverse the rectangularpath of travel in a counterclockwise direction, eventually the shuttlerail 142 will return to an alignment with the stationary rail 122.

As discussed previously, pallet 120 includes a pair of downwardlyprojecting tangs 134, 136. Tang 136 was previously sandwichingly engagedbetween a powered roller 150 and a pinch roller 152 as the pallet 120was transferred longitudinally from the shuttle rail 142 to thestationary rail 124. While the powered roller 150 is fixed in place, thepinch roller 152 and another pinch roller 154 are supported by the base144, and thereby they both move laterally with the shuttle rail 142.When the shuttle rail 142 is moved back to alignment with the stationaryrail 122, the pinch roller 154 will pair with another powered roller 156to transfer the pallet 118 from the stationary rail 122 to the shuttlerail 142.

FIG. 5 is a functional block diagram depicting a control circuit 158that is capable of circulating the two pallets 118, 120 along the samerectangular path of travel to load trays 108 to the pallets 118, 120 onone of the stationary rails 124 while simultaneously presenting thetrays 108 to the pick and place device 102 on the other of thestationary rails 122. A processor based controller 160 receives palletposition data from the linear encoders associated with the respectivestationary rails 122, 124 in blocks 162, 164. The controller 160 isinformed by block 166 when the pick and place device 102 has completedprocessing on a presented row, and on a presented tray 108 for thatmatter. Workpiece information is provided in block 168 that indicatessuch things as the incremental distance between rows in the tray 108,the number of rows in the tray 108, and the number of trays 108 to beprocessed.

From that input data the controller 160 powers the sets of motorsdriving the powered rollers represented by blocks 170, 172 toselectively position the pallets 118, 120. In blocks 174, 176 thecontroller 160 actuates the cylinders 146, 148 to move the pallets 118,120 between the two stationary rails 122, 124. Dwell time for traystacker and destacker operations are controlled in blocks 178, 180 toremove a fully presented tray from the pallet 118, 120 and place anunpresented tray to the same pallet 118, 120, respectively.

Slight longitudinal misalignments can occur between the shuttle rails142, 143 and the stationary rails 122, 124 as the shuttle rails 142, 143are moved back and forth. To compensate for any such misalignments, endsof both the stationary rails 122, 124 and the shuttle rails 142, 143 canbe provided with longitudinally extending slits 182 (FIG. 4). FIG. 6 isan end view of the stationary rails 122, 124 and the shuttle rails 142,better showing the slits 182. In this illustrative embodiment there arefour bearing surfaces 184 that supportingly engage the pallet 118, 120and its contents. Each bearing surface 184 is deflectable by theadjacent slit 182, providing a smoother transition as the bearingstransition between the stationary rails 122, 124 and the shuttle rails142, 143.

FIG. 7 is an isometric depiction of the tray feeder 104 described withrespect to FIG. 4, with the addition of an automated tray stacker 186for removing trays 108 from the pallets 118, 120, and an automated traydestacker 188 for placing trays 108 to the pallets 118, 120.

The tray stacker 186 has a framework 190 that is vertically moveable bya fluid powered cylinder 192. The framework 190 defines an opening 194through which a tray 108 can pass. Retractable fingers 196 on opposingsides of the opening 194 are first retracted to pass the fingers 196into operable alignment with the tray 108 to be removed. The fingers 196are extended to contactingly engage the tray 108, and the framework 190is then withdrawn to lift the tray 108 from the pallet 118, 120. Thetrays 108 stack up on the framework 190 as successive trays 108 areremoved from the pallets 118, 120.

The tray destacker 188 works in basically the reverse. That is, a stackof trays 108 are placed on a framework 198 that is vertically moveableby another fluid powered cylinder 200. The framework 198 is lowered toplace the bottom tray 108 in a stack onto the waiting pallet 118, 120.Fingers 202 are then retracted and the framework 198 moved upward torelease the stack of trays 108 on the pallet 118, 120. The fingers 202are then extended again to grippingly engage the next tray 108 up in thestack, and lift it and the rest of the stack of trays 108 away from thepallet 118, 120.

FIGS. 8-13 depict snapshot steps within a method for continuouslypresenting the trays 108 (not shown) to the pick and place device 102(not shown). FIG. 8 shows the pallets 118, 120 oriented in an end-to-endlongitudinal alignment with pallet 118 leading pallet 120 in thecounterclockwise path of travel. The controller 160 moves the pallets118, 120 longitudinally along the stationary rail 122 and the shuttlerail 142 by selectively powering the respective set of motors to presentrows of workpieces in the trays 108 to the pick and place device 102. InFIG. 8 the tray 108 supported by pallet 118 has been fully presented,such that rows in the tray 108 supported by pallet 120 are now beingpresented to the pick and place device 102.

FIGS. 9-13 depict the parallel processing by the controller 160 toincrementally move the pallet 120 to present rows of workpieces to thepick and place device 102 while simultaneously loading a new tray ofworkpieces to the pallet 118.

In FIG. 9 the controller 160 has actuated the fluid powered cylinder 146to move the shuttle rail 142 into alignment with the other stationaryrail 124. In FIG. 10 that alignment has been achieved, and thecontroller 160 dwells at that position long enough for the stacker 186(FIG. 7) to remove the fully presented tray 108 from the pallet 118. InFIG. 11 the controller 160 moves the empty pallet 118 longitudinally onthe shuttle rail 142 and then on the stationary rail 124, in an oppositedirection as to that which it traversed the other stationary rail 122.The controller 160 will also actuate the other fluid powered cylinder148 to move the other shuttle rail 143 into alignment with thestationary rail 124 before the pallet 118 reaches the end of thestationary rail 124. All the while, the controller 160 continues toincrementally advance the pallet 120 to continuously present rows ofworkpieces to the pick and place device 102.

In FIG. 12 the pallet 118 is now supported upon the shuttle rail 143.Again, the controller 160 dwells at that position long enough for thedestacker 188 (FIG. 7) to place a new tray 108 onto the pallet 118. FIG.13 shows that when the other pallet 120 has been moved sufficiently toclear a space, the controller 160 will again actuate the fluid poweredcylinder 148 to reorient the pallet 118 and the pallet 120 in theend-to-end longitudinal alignment, but now with pallet 120 leadingpallet 118. The pallets 118, 120 are moved longitudinally until the tray108 on pallet 120 is fully presented, and then the steps described aboveare repeated to replace the tray on pallet 120 while simultaneouslypresenting rows of the tray 108 on pallet 118 to the pick and placedevice 102.

The maximum throughput velocity with which the pallet 118, 120 canpresent a tray to the pick and place device 102 depends on the cycletime that is necessary for the pick and place device 102 to process allthe workpieces in a row. Preferably, the pallets are cooperatively movedso that the new tray 108, such as the one being delivered by pallet 118in FIG. 13, is available to the pick and place device 102 as if it werea physical continuation of the tray 108 on pallet 120. In other words,to provide an efficient, continuous and uninterrupted supply ofworkpieces 106, the pallet 118, 120 presenting the workpieces 106 isincrementally moved at a maximum throughput velocity. The other pallet118, 120 is moved, unloaded, loaded, and reoriented in longitudinalalignment at a throughput velocity such that the cycle time necessary toprocess two adjacent rows presented in one of the pallets 118, 120 issubstantially the same as the cycle time necessary to process the lastrow presented in one of the pallets 118, 120 and the first row presentedof the other pallet 118, 120.

Generally, the claimed embodiments as described herein cover a workpiecepresentment device incorporating a two-axis pick and place device and ameans for presenting a continuous supply of workpieces to the pick andplace device. For purposes of this description and meaning of theappended claims, the term “means for presenting” is expressly limited tothe structural embodiments described herein and the structuralequivalents thereof. That is, the term “means for presenting” does notinclude previously attempted solutions such as those employing athree-axis pick and place device, and such as those that momentarilystarve the pick and place device for workpieces while a new tray ispresented.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the present invention have been setforth in the foregoing description, together with details of thestructure and function of various embodiments of the invention, thisdetailed description is illustrative only, and changes may be made indetail, especially in matters of structure and arrangements of partswithin the principles of the claimed embodiments to the full extentindicated by the broad general meaning of the terms in which theappended claims are expressed. For example, the particular elements mayvary in type or arrangement without departing from the spirit and scopeof the claimed embodiments.

In addition, although the embodiments described herein are directed topresenting workpieces to an assembly line, it will be appreciated bythose skilled in the art that the claimed subject matter is not solimited and various other systems can utilize the present embodimentswithout departing from the spirit and scope of the claimed invention.

1. A tray presentment system for a processing device, comprising: a pairof parallel stationary rails; first and second shuttle railsrespectively disposed adjacent first and second ends of the stationaryrails, each shuttle rail independently moveable laterally to alongitudinal alignment with a selected one of the pair of stationaryrails; and a control circuit configured to circulate only two palletssimultaneously in the same rectangular path of travel to load trays tothe pallets on one of the stationary rails while presenting the trays tothe processing device on the other stationary rail.
 2. The traypresentment system of claim 1 wherein the stationary rails and theshuttle rails define longitudinal slits at their adjacent ends so thatbearing surfaces of the rails supporting the pallets during movement candeflect to compensate for any incidental misalignment.
 3. The traypresentment system of claim 1 wherein the control system comprises fluidpowered cylinders that selectively move the shuttle rails laterally. 4.The tray presentment system of claim 3 wherein the control systemcomprises motors that frictionally engage the pallets in moving themlongitudinally along the rails.
 5. The tray presentment system of claim4 wherein the control system comprises a first set of motors thatfrictionally engage a first reference surface defined by each palletwhen moving the pallets along one of the rails, and a second set ofmotors that frictionally engage a second reference surface defined byeach pallet when moving the pallets along the other rail.
 6. The traypresentment system of claim 5 wherein each motor directly drives apowered roller that is paired with a pinch roller to sandwichinglyengage the reference surface between the rollers.
 7. The traypresentment system of claim 6 wherein a base supporting the shuttle railin lateral movement also supports a first pinch roller and a secondpinch roller, the first pinch roller cooperating with a powered rollerdriven by a motor in the first set of motors to move each pallet on oneof the rails and the second pinch roller cooperating another poweredroller driven by a motor in the second set of motors to move each palleton the other rail.
 8. The tray presentment system of claim 6 wherein thestationary rail on which the pallets present trays to the processingdevice is sized to simultaneously move both pallets longitudinally in anend-to-end relationship, so that a cycle time associated with presentingtwo adjacent rows in one of the pallets is substantially the same aspresenting the last row of one of the pallets and the first row of theother pallet.
 9. The tray presentment system of claim 1 comprising anautomated tray stacker that removes trays from the pallets.
 10. The traypresentment system of claim 1 comprising an automated tray destackerthat places trays to the pallets.
 11. A method for presenting trays to aprocessing device, comprising: (a) orienting first and second palletssupporting first and second trays, respectively, in an end-to-endlongitudinal alignment with the first pallet leading the second pallet;(b) moving the pallets in a first direction to present rows of the traysto the processing device; (c) shuttling the first pallet laterally outof the longitudinal alignment when all its rows have been presented; (d)moving the first pallet in a second direction substantially opposite thefirst direction while continuing to move the second pallet in the firstdirection to present rows to the processing device; (e) placing anothertray on the first pallet; (f) shuttling the first pallet laterally toreorient the first and second pallets in the end-to-end longitudinalalignment with the second pallet leading the first pallet; and (g)moving the pallets in the first direction to present rows of the traysto the processing device.
 12. The method of claim 11 comprising: (h)shuttling the second pallet laterally out of the longitudinal alignmentwhen all its rows have been presented; (i) moving the second pallet inthe second direction while continuing to move the first pallet in thefirst direction to present rows to the pick and place device; (j)placing another tray on the second pallet; (k) shuttling the secondpallet laterally to reorient the first and second pallets in theend-to-end longitudinal alignment with the first pallet leading thesecond pallet; and (l) moving the pallets in the first direction topresent rows of the trays to the processing device.
 13. The method ofclaim 12 comprising repeating steps (c) through (l) sequentially until apredetermined number of trays has been presented.
 14. The method ofclaim 13 wherein steps (e) and (j) comprise extending an automated endeffector to remove a tray from the pallet.
 15. The method of claim 13wherein steps (e) and (j) comprise extending an automated end effectorto place a tray on the pallet.
 16. The method of claim 13 wherein steps(b), (g), and (l) comprise incrementally moving at least one of thepallets to present each row to the processing device for an intervalassociated with a cycle time necessary to process the entire row. 17.The method of claim 16 wherein steps (b), (g), and (l) comprisecooperatively moving both pallets so that a cycle time necessary toprocess two adjacent rows presented in one of the pallets issubstantially the same as a cycle time necessary to process the last rowpresented in one of the trays and the first row presented in the othertray.
 18. The method of claim 13 wherein steps (b), (d), (g), (i), and(l) are characterized by moving the pallets by frictionally engaging areference surface of each pallet between a powered roller and a pinchroller, and position controlling the pallets by encoders.
 19. The methodof claim 13 wherein steps (c), (f), (h), and (k) are characterized bymoving the pallets with fluid powered cylinders.
 20. A workpiecepresentment system, comprising: an only two-axis pick and place device;and means for presenting a continuous supply of workpieces to the pickand place device.